title: Electronic excited states of a strongly correlated organic radical 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA) adsorbed on a Si(001) surface.
abstract: Electronic excited states of a strongly correlated organic radical, 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA), adsorbed on a Si(001) surface were investigated by means of two-photon photoemission spectroscopy (2PPE) to elucidate the functional organic thin-film formation on a typical semiconductor substrate. The spectra were interpreted with the aid of density functional theoretical calculations. The unpaired electron of TTTA forms a covalent bond with the dangling bond of the Si-dimer initially, and there are resonant states of TTTA to Si near the surface. The molecules adsorbed at room temperature form dimers having diamagnetic properties at thicknesses of a few monolayers, while the paramagnetic phase appears at multilayer thickness. From the change in the work function, the orientation of the adsorbed TTTA molecules was determined to change depending on the thickness of the adsorbed layer.
authors.affiliation: Faculty of Engineering/Science, Yokohama National University, Tokiwadai 79-5, Hodogaya-ku, Yokohama 240-8501, Japan. ken1@ynu.ac.jp.
authors.forename: K
authors.initials: K
authors.lastname: Shudo
authors.forename: T
authors.initials: T
authors.lastname: Satake
authors.forename: T
authors.initials: T
authors.lastname: Shimatsu
authors.forename: M
authors.initials: M
authors.lastname: Uchiyama
authors.forename: J
authors.initials: J
authors.lastname: Takeda